Building an oak telescope

You might not think about the finish of your homemade telescope but if it’s build from solid oak you probably should. [Gregory Strike] built this 8″ telescope a few years back but just posted about it a few days ago. The optics are quite expensive but the rest of the build was done dirt cheap and he did a great job of it.That includes taking care to finish the oak boards that make up the octagonal body of the instrument.

Hope I’m not feeding a troll. The size refers to the diameter of the objective lens in a refractive telescope or the diameter of the primary mirror in a Newtonian telescope. I apologize if that was a intended as a serious comment

If you do this make sure you mount your optics on an interior metal frame instead of directly to the wood. Wood changes shape quite drastically(as far as detailed optics are concerned) in different temperature and humidity.

The mirror itself has a 8 inch diameter. The bigger the mirror the more light you can gather (it’s like having an 8 inch pupil). The OTA (tube) itself is 4ft long. And yes, the scope is definitely a pain to lug around! :) But at least it looks good sitting in my dining room!

@j9: That type of axis/azimuth mount is actually quite common for large home-built telescopes meant for observing deep sky objects. It lets you cheaply mount a pretty large telescope, and it breaks down easily for transport. Obviously you can’t use it for photography like you would an equatoral mount, but otherwise it’s a pretty effective choice.

It’s fine, if a bit too heavy. Dimensional stability isn’t really that big of a deal for most amateur scopes which are used visually. Slight expansion along the length of the telescope tube results in a small shift in focus, but no other significant errors. Shifts in the tube radius will generally keep a centered diagonal centered, and cause no real additional problem.

It’s common to use cardboard tubes used in the concrete industry (“Sonotube”, and related products) as telescope tools. Despite the apparent cheapness, it’s actually a fine material for scopes of this size. It’s cheap, easy to paint, strong enough, and easily available. Yes, you have to waterproof them (I like to use a durable poly floor paint) and I wouldn’t leave them out in the rain or in a high humidity environment, but would you do that to a camera?

One of the past members of our workshop, Phil Alotis, did a similar scope in years past. It appeared in Sky & Telescope, and was called Christine. You can see it on the left here:

If my memory serves, his wife was the motivating factor, she said that if he was going to store the scope inside, it had to look pretty. The resulting scope is beautiful, but massive. I think the mass means that it cools relatively slowly, which can be a disadvantage as well. I believe it was also an award winner at the Riverside Telescope Maker’s Conference.

@Gregory… Ok, now I get it:) I know very little about Telescopes. Obviously… So, thanks for the explanation. Guess, to you guys. It’s like us computer geeks saying… I run Fedora Linux on my Box. I think you should just mount that tele in the back of my 76 Blazer 4×4 and then help me get the 200+lbs Removable Top off, so we can drive out to the Country to see the stars:)

Dobsonian type telescopes are made of everything and anything. They’re real time viewing instruments (no photography, no auto-tracking) so it’s all about the size and quality of the optics. 8″ isn’t very big these days for dob’s – especially if you have to lug around a heavy mount and tube.

temperature has little effect. it is the humidity that screws with wood. wood expands along the grain not across it. If you treat your wood with a proper finish you lock out all the moisture and can make it very very stable.

Clyde Tombaugh didn’t discover Pluto with a handmade telescope, but he did land a job at the Lowell observatory as a young man after submitting sketches of Jupiter and Mars that he _did_ make using a home made telescope of 9″ aperture. He constructed a larger 16″ telescope that was bought by an amateur after Clyde’s death, and reassembled. Check it out:

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